Project Summary Negative symptoms are a core feature of schizophrenia defined as the loss of normative motivation and/or expression. This dimension of psychopathology is distinct from other aspects of the illness and highly predictive of poor community-based functional outcomes. However, pharmacological and psychosocial treatments for negative symptoms have demonstrated limited effectiveness. To address this critical unmet need in schizophrenia therapeutics, the NIMH sponsored a consensus development conference to delineate research priorities for the field and stimulate treatment development. The primary conclusion of this meeting was that next-generation negative symptom rating scales should be developed to address methodological and conceptual limitations of existing instruments. Two next-generation clinical rating scales resulted from the NIMH consensus development conference that were intended for use with adult populations presenting with established psychotic illnesses. However, the consensus conference did not discuss development of assessments specific to youth at ultra-high risk (UHR) for developing psychosis (i.e. adolescents/young adults meeting criteria for a prodromal syndrome). Given that negative symptoms are highly predictive of the transition to diagnosable psychotic illness, enhancing our ability to detect negative symptoms in UHR youth is paramount. Existing scales designed to assess negative symptoms in UHR youth have conceptual and methodological limitations and scales designed for adults with diagnosable illness do not meet the unique needs of the UHR population. New scales specifically designed to assess negative symptoms in UHR youth are needed to accurately chart mental illness trajectories and determine when, where, and how to intervene. The current study aims to extend the scale development aims of the NIMH consensus development conference to the UHR population by taking an iterative, data-driven approach to creating a new measure, the Prodromal Inventory for Negative Symptoms (PINS). A beta version of the PINS was developed that displayed promising psychometric properties. Two studies will be conducted to refine the beta version and arrive at a final scale based on state-of-the-art statistical methods, with data collected at 3 sites with ongoing UHR research programs. Study 1 will include a large, representative, and diverse sample of UHR youth (n = 180) and evaluate the psychometric properties of the beta version. To determine how the beta version should be revised, analyses will be conducted to determine item selection, modification, and retention, including Item Response Theory, confirmatory factor analysis, item-level analyses, within- and between-site inter-rater reliability, and analyses of convergent and discriminant validity. In study 2, psychometric properties of the revised scale will be evaluated in a sample of UHR youth (n = 120) who will be followed longitudinally. Analyses of the final scale will evaluate measurement stability, internal consistency, inter-rater reliability, prediction of the transition to diagnosable psychotic illness, factor structure, convergent validity, and discriminant validity. This iterative, data-driven scale development process will provide the field with a next-generation negative symptom scale that meets the unique assessment needs of the UHR population.